In copending U.S. patent application Ser. No. 499,671, filed Aug. 22, 1974, there is disclosed an electrically pumped, heterojunction, distributed feedback, solid state diode laser which utilizes a grating or periodic structure situated at a heterojunction interface. The periodic structure interacts with the light produced by the active laser medium to provide the feedback necessary for lasing. The periodic structure is produced by an interferometric exposure technique which utilizes a beam splitter and two mirrors to direct two laser light beams of equal intensity and equal polarization upon a photoresist with equal angles of incidence. As is apparent, a periodic structure with a period on the order of 3600 A is often difficult to produce.